<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>阴影</title>
    <style>
<!--
  https://v.douyin.com/i2tn7Yy/
  对像素做阴影
  filter: drop-shadow(0 0 10px #000);
  对边框做阴影
  box-shadow: 0 0 10px #000;
-->
      .yy {
       filter: drop-shadow(0 0 10px #000);
       box-shadow: 0 0 10px #000;
      }
    </style>
</head>
<body>
<img class="yy" src="http://www.firefox.com.cn/media/protocol/img/logos/firefox/browser/logo.eb1324e44442.svg" alt="一只蒲公英">
</body>
</html>